Crossover Shipgirls: Building a Dimensional Empire from Scratch

Between Alpha Centauri and the Solar System.

In the dark void of space, the First Trisolaran Fleet advanced at ten percent of light speed.

They had departed from their homeworld 200 years ago. According to their original plan, they would arrive at the Solar System in over 200 more years.

To annihilate the humans there and secure a stable new home for the Trisolaran civilization.

With sophons locking down Solar System technology, barring any accidents, the human United Fleet would not even be able to defeat a Droplet probe.

This was supposed to be a great victory for Trisolaris.

Then—an accident did happen.

The Droplet was captured by an alien civilization, and the Trisolaran homeworld was annihilated by the Fallen Star Lance.

At this moment, although the three stars of Alpha Centauri still shone brightly to the naked eye, every Trisolaran crew member knew that it was now a lifeless, dead system.

Only a massive black hole and wreckage orbiting its accretion disk remained.

”...”

The commander of the First Fleet found himself in a very awkward situation.

They had set out to conquer the Solar System, yet their homeland had perished first.

In the Solar System, there was also a Juggernaut-class ten-gigaship that no Trisolaran dared provoke.

The First Fleet did not have enough fuel to return, and even if they could, returning was meaningless.

Continuing toward the Solar System according to the original plan would only be seeking death.

Thus, the First Fleet was now lost and confused.

”The enemy has already dispatched a pursuit fleet. We must act quickly.”

”We cannot return to the homeworld, nor can we approach the Solar System. Our only option is to seek another star system…”

Within the First Fleet, discussion began.

Trisolaran communication was extremely efficient, and they quickly reached a conclusion.

”For the continuation of our species, we must abandon a portion of our ships and disperse.”

The fleet’s fuel was only enough for 2–3 more light-years of travel. For long-distance voyages, resources from most ships would have to be concentrated into a few.

Then they would advance toward other star systems.

”Do it.”

The commander of the First Fleet gave the order.

”90% of crew members are to dehydrate. Concentrate resources into 60 starships and scatter to escape.”

”Move fast—the enemy won’t give us much time.”

Trisolarans could preserve themselves for very long durations in a dehydrated state. In a sense, they were well-suited for interstellar travel.

The fleet gradually drew closer together. Some crew voluntarily dehydrated, expelling excess bodily fluids and shrinking into thin, dried sheets.

Suddenly—

Vmmm—

The fleet’s detectors blared alarms.

The Starsea Empire’s fleet was faster than they had imagined.

In the distance, the stars suddenly flashed with a fierce white light. A pale-blue battleship, inlaid with cyan patterns, emerged first from the void.

”Northern Union First Fleet, Sovetsky Soyuz, reporting in.”

”I have discovered the First Trisolaran Fleet—total count: 1,024 ships. Commander, should we annihilate them all?”

On the bridge, a shipgirl with long cyan hair, stern and severe in expression, holding an icy-blue scepter, turned to Setsuna for instructions.

”Capture a few starships and a small number of Trisolarans. Bring them back for research. Purifier and Observer-chan love dissecting aliens, don’t they?”

Setsuna gave the order lazily.

”Understood.”

From behind Sovetsky Soyuz, more Northern Union ships emerged—Kirov, Chapayev, Tashkent, and the entire Northern Union fleet.

Alongside them were four Illustrious-class armored carriers dispatched for support.

”Destroy them! Let them taste the Soviet iron fist!!!”

Tashkent and several destroyers clenched their fists eagerly.

This was their first time properly fighting aliens.

”We are Royal Navy shipgirls, thank you very much…”

Formidable and Victorious both sighed in exasperation.

Activating sensors, they scanned the distant Trisolaran fleet.

The design philosophy of Trisolaran starships was completely unlike Earth’s. Complex—that was the first impression.

Their hull structures seemed disordered, following design rules unique to the Trisolaran world.

The ships were enormous, more than ten times larger than the United Fleet’s, yet before shipgirl warships, they still appeared small and fragile.

The 1,024 starships all shared the exact same design, equipped with antimatter propulsion and several high-energy weapons.

”Comrades, attack!!”

Sovetsky Soyuz gave the cold order.

Shwoom—Shwoom—Shwoom—

The crushing battle began in an instant.

For the shipgirls, fighting the Trisolarans was no different in difficulty than the Eternal Snowfall fighting the United Fleet.

After all, they were merely sub-light natives who had only just stepped into the space age.

Boom!!!

The first volley was a broadside from battleship and battlecruiser shipgirls.

Dozens of multicolored energy torrents spewed forth from their massive axial cannons, streaking across hundreds of millions of kilometers of space.

The forward rows of the Trisolaran First Fleet were instantly reduced to particles.

Next, carrier shipgirls unleashed thousands of space-based aircraft, while destroyer shipgirls launched countless space missiles.

It was only after sustaining two rounds of devastating attacks that the Trisolaran fleet realized what was happening.

They desperately tried to counterattack, but immediately discovered that, due to the enormous technological gap, they could not even fight back in space warfare.

The two sides were separated by over 300 million kilometers—about 20 light-minutes.

The Trisolarans’ detectors could only see images of the shipgirl fleet as they had been 20 minutes ago.

By the time they saw the shipgirls opening fire, their fleet had already been shattered to pieces.

A 20-minute delay meant there was no chance of hitting the enemy in interstellar warfare.

If the shipgirls widened the distance further, the information delay could stretch to two hours, two days, even two weeks or months…

At that level of informational disparity, space combat became nothing more than one-sided slaughter.

Thousands of space-based aircraft activated their short-range jump drives, instantly leaping close to the First Fleet.

Dense energy rays and kinetic cannons tore the fleet apart.

After a brief clash and chaos, the Trisolaran commander gave a single order:

”Flee.”

All starships activated their engines at maximum power, scattering in all directions.

”A pursuit battle, huh? Tch.”

Carrier-based fighters and starships split into several groups, hunting down the fleeing enemy across the vastness of space.

For some younger shipgirls, this was their first proper interstellar war. Even though the enemy were only sub-light natives, they were excited.

Opening full fire, light streaked across the void like a meteor, performing high-speed, complex maneuvers.

Beams of every color interwove across the cosmic night. One after another, enemy ships erupted into explosions.

Half an hour later—

In the thin nebula, only the wreckage of the Trisolaran fleet remained.

They had been reduced to interstellar dust clouds, scattered across empty space.

Several ships had their weapons modules destroyed but remained intact.

The Angeloid led boarding actions against them, seizing control of the vessels and capturing all the crew aboard.

”Report, Commander—the First Trisolaran Fleet has been completely annihilated.”

”Enemy losses: 1,020 ships destroyed, four ships captured. Our forces suffered no casualties, and all ships remain in perfect condition.”

Sovetsky Soyuz once again reported to Setsuna.

”Very good.”

Setsuna nodded.

”Send a few back for Siren-chan to dissect. The rest—lock them up in a zoo.”

”Grey suggested we build an alien zoo in the Trisolaran world. We’ll lock all these aliens inside, and maybe teach them some circus tricks—jumping through fire rings, walking tightropes, that sort of thing.”

”Understood!”

After a simple reformation, part of the Northern Union fleet escorted the captives back to the Solar System.

The rest kept their radars active, scanning nearby systems in search of other alien fleets.

Cheering joyfully, they reignited their engines.

”Long live the Northern Union! Let’s go shatter these decaying alien civilizations, Davai Comrade!!!”

...

At the other end of the Solar System.

On the fleeing Natural Selection, Blue Space, Ultimate Law, and other ships, the crew had fallen into an eerie silence.

Zhang Beihai stared at the signals continuously coming from Earth. Since awakening and joining the Space Force, he had never imagined such absurd events could occur.

The Trisolaran civilization had been completely destroyed, and their threat had vanished.

The Starsea Empire had first crushed the United Fleet, then wiped out the Trisolaran world.

With undeniable technological superiority, they now ruled the entire Solar System and were preparing to sweep the surrounding starfields.

At this moment, in a sense, the Natural Selection and the ships chasing it—Blue Space, Ultimate Law, Enterprise, and Deep Space—were the only five remaining warships of the United Fleet.

Clack—

After stepping out of his spherical cabin, Zhang Beihai walked through the corridor, opened a door, and entered the largest spherical hall aboard the warship.

At the center of the sphere floated a formation composed of fleet officers and soldiers.

Only the first layer was real; the upper and lower layers were holographic projections.

The holographic formations were composed of soldiers from the four pursuing ships. In front of the three-tiered formation, five senior colonels, including Dongfang Yanxu, stood in a row and saluted him together:

”Asia Fleet, Blue Space!”

”North America Fleet, Enterprise!”

”Asia Fleet, Deep Space!”

”Europe Fleet, Ultimate Law!”

Dongfang Yanxu was the last to salute: ”Asia Fleet, Natural Selection!”

”Senior, you have preserved five interstellar warships for humanity—this is now the entirety of humanity’s space fleet. From this moment on, we place ourselves under your command!”

”...”

Zhang Beihai felt conflicted.

The United Fleet being defeated by the Trisolarans had been within his expectations. But the sudden emergence of another human civilization was a complete surprise.

Onboard the Natural Selection, after receiving the salutes of the other captains, his expression did not change. His gaze remained calm as still water.

”Senior, what should we do now?”

Dongfang Yanxu asked.

”Earth has been completely occupied by the Starsea Empire. The ground resistance forces were annihilated within half a day. They are now rebuilding the government.”

”The other side seems to be an imperial civilization. It’s hard to imagine a feudal empire in the space age? …”

Zhang Beihai shook his head.

”Dongfang, don’t measure another civilization by our values, nor waste time criticizing systems—those are empty illusions.”

”If the other side is stronger than us, we must face reality.”

”...”

Dongfang Yanxu fell silent. Zhang Beihai was a soldier of the Common Era, not impressed by the so-called freedom and equality of the New Humans.

”Earth hasn’t contacted us yet. Should we return, or continue fleeing?”

The captain of the Ultimate Law asked.

”...”

The five captains fell into brief silence.

”The Starsea Empire has demanded that humanity never again retain any space fleet. If we return, we must hand our ships over to them.”

”Then return to life in the pre-space era.”

Chu Yan spoke.

The crew’s expressions darkened.

Each of them had developed some attachment to their ships. Handing them over felt unbearable.

What’s more, once they returned, they would never again have the chance to set foot into space.

”And if we continue to flee? They seem not to care about us~”

Dongfang Yanxu opened the star map on the holographic interface.

”As the last free humans, we could rebuild a new civilization in the universe.”

”The nearest star system where we can resupply is… toward Cygnus, star NH558J2.”

”It has two planets, both gas-liquid giants similar to Jupiter. Not suitable for human habitation, but capable of supplying fusion fuel.”

”...”

The captains fell silent.

Cygnus was 18 light-years away from the Solar System.

Considering the difficulties of the journey, it would take about 2,000 years to reach it.

--

None of their ships had the supplies to reach that destination.

Unless…

They concentrated the resources of the other ships and placed the majority of the crew into hibernation.

”!”

The same fleeting thought crossed the minds of the five captains.

Terrifying and dark.

”…Let’s return for now. We’ll decide later.”

Zhang Beihai sighed.

Just as he was about to turn and leave—

Zzz—

The holographic interface flickered with white static as the Eternal Snowfall’s communication connected in.

With tachyon communication, there was no delay at all.

Setsuna glanced at the five captains standing in perfect formation, then at Zhang Beihai, who was frowning.

The scene felt oddly familiar.

”Stop. Don’t run. If you keep running, you’ll end up playing interstellar battle royale again.”

”Just come back first.”

”???”

Over five thousand crew members and the captains stared at Setsuna in shock.

For a moment, they wavered between suspicion and confusion.

”I guarantee your safety. Return.”

Setsuna smiled.

If he let them follow the original storyline and flee again, the final victor would probably still be Chu Yan.

As for Zhang Beihai, Ding Yi, and a few others—they were among the rare few on Earth who actually had brains.

”….”

The crew turned to Zhang Beihai, awaiting his decision.

”Return.”

Zhang Beihai sighed.

”If they want to pursue us, we can’t escape anyway.”

”For now, we still have some room for negotiation.”

Vmmm—

The warships slowly turned back toward the Solar System.

...

The Natural Selection and the other ships spent several days making their way back to the Solar System.

As soon as they passed Mercury’s orbit, even with the naked eye they could see the massive starship hovering above the Sun.

The Juggernaut hung silently over the star, with the boundless starry sky above and the blazing star below.

The Milky Way refracted across its towering hull, forming a silver-white halo that intertwined with the burning sunlight, solemn and awe-inspiring.

Facing such a planetary-class giant ship up close, the crew couldn’t help but tremble.

Especially when they thought about its ability to destroy stars—then saw it casually parked atop the Sun—their fear only deepened.

Clack—

A shuttle piloted by the Angeloid came to receive them.

Zhang Beihai, Chu Yan, and a few others whose names were called boarded the shuttle and made their way toward the Eternal Snowfall’s bridge.

They noticed that, in the space above the Sun, a small starbase-town had already been constructed.

Tens of thousands of Bulin bustled about, wielding tools and building structures for the starbase at a speed visible to the naked eye.

”A space city on the Sun? How…?”

Chu Yan frowned, unable to hide the shock in his eyes.

”And those workers? Are they AI? Why are they building a space city with hammers and drills?!”

”….”

Zhang Beihai didn’t understand either. In his imagination, a spacefaring civilization would use intelligent AI or engineering robots for space construction.

Why was a starbase of an FTL civilization being built purely by hand?!

After pondering for a long while, none of the captains could make sense of it.

They could only chalk it up to divine-level civilization power, beyond their comprehension.

Twenty minutes later—

They entered the Eternal Snowfall’s bridge and met Setsuna.

Seeing an Eastern-faced general, both Chu Yan and Zhang Beihai felt a faint sense of kinship.

Most shipgirls had been dispatched to eliminate aliens and conduct reconnaissance, while a few remained on the bridge.

The sight left them stunned.

”Their captains… are all girls? …”

”Wait, this moon-sized ship has no crew?!”

”A 3,600-kilometer-long unmanned starship?!”

They were struck speechless, overwhelmed by shock after shock.

The technological gap between humanity and the Starsea Empire was clearer than ever.

”Ahem, simply put, I’d like to talk with you.”

Setsuna gestured for them to sit, his gaze settling on Zhang Beihai and Chu Yan.

Debating endlessly with Earth’s petty schemers was a waste of time—but for these two, Setsuna was willing to spend some effort.

”As you can see, the Starsea Empire has fully taken control of the Solar System. Soon, a starbase above the Sun will be completed.”

”We will conduct research here on the Trisolaran universe—its unique technologies and alien civilizations.”

He explained the situation succinctly.

”As for you… I’ll give you two options.”

Setsuna thought for a moment.

”Live on Earth. From now on, Earth will no longer have a space fleet. You can find something else to do—the United Government will guarantee you a comfortable life.”

”Or, continue voyaging into the stars. I can provide you with some supplies.”

”….”

The group fell into deep thought.

That they were even being given a choice meant their worth was being acknowledged.

On Earth, they could live safe, stable lives—but would never again reach for the stars.

The captains exchanged glances, whispered briefly among themselves.

Zhang Beihai was the first to speak:

”There’s no need for us to return to Earth.”

He shook his head and looked at Setsuna.

”Once humanity set foot into the stars, it became a new civilization.”

”I’ve always been fond of the Natural Selection. It was our dream two centuries ago. I did many things, by any means necessary, just to make the starship a reality.”

”If I were to choose my own resting place, let it be alongside my starship.”

”As the leader of an interstellar civilization, you should understand what I mean.”

Chu Yan and the other captains nodded in agreement.

”….”

”Indeed.”

Setsuna gazed at the starlight outside, thoughtful.

”Leaving you to rot with those petty schemers on Earth would be wasting your talents.”

...

Two weeks later—

A small starbase above the Sun was completed.

The Natural Selection and Blue Space slowly departed from their berths.

Their hulls and engines had undergone complete reconstruction, upgraded to a technological level humans could comprehend. They were refitted with lightspeed engines and more advanced ion weapons.

Fully loaded with supplies sufficient to sustain thousands of years of interstellar travel, the ships set out on their journey.

The two vessels were commanded by Zhang Beihai and Chu Yan, with Ding Yi serving as the onboard scientist, leading those willing to leave the Solar System and explore the deep void.

Although the Trisolaran schemers were loathsome, among them were still dreamers who longed for the stars.

The rest, unwilling to risk such peril, returned to Earth.

From then on, apart from the Solar System ruled by the Starsea Empire, another wandering human civilization emerged in the void—

—Starship Earth.

”Thank you for your support. We hope that one day we can repay your gift.”

Zhang Beihai saluted Setsuna via holographic interface.

”Go.”

Setsuna waved his hand.

Refitting the two ships had been a trivial task. For safety and maintenance, he had only installed lightspeed engines.

Even so, in this universe, it was more than enough.

Originally, Blue Space had been able to preserve humanity’s spark even in its impoverished state, eventually mastering miniature worlds and lightspeed ships.

Now, Starship Earth was starting from a much higher foundation, with a stronger roster. Setsuna was eager to see how far this wandering civilization could go.

”Perhaps one day, Starship Earth will become a civilization as great as yours. Let us meet again, in Perseus, in Andromeda, or even farther into the universe.”

The two captains saluted Setsuna one last time.

Boom!!!

The two ships ignited their engines, vanishing into the deep void.

”Until we meet again, Commander Setsuna.”

—

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